Method and device to obtain percutaneous tissue samples

ABSTRACT

A new method and design for a percutaneous biopsy system that cuts only the tissue lesion specimen and that does not penetrate through or beyond the targeted tissue into intact tissue. The proposed mechanism operates only in the targeted lesion space and leaves healthy or unsuspicious tissue intact. The proposed biopsy mechanism will cut the specimen in front of the tip of the guiding needle. The device may be image guided by ultrasound, any x-ray based modality or magnetic resonance (MRI).

FIELD OF THE INVENTION

The present invention relates to a percutaneous biopsy device that cutsa suspicious desired tissue specimen, leaving undesired tissue unharmed.This application claims priority to U.S. Ser. No. 60/634,386, whichincorporated herewith by reference.

BACKGROUND OF THE INVENTION

Medical biopsy is a technique to obtain tissue samples for pathologicdiagnostics. Open surgical biopsies are still the standard techniques inmany medical fields. There are basically two principle percutaneousbiopsy techniques for the interventional or minimally invasive biopsymarket, which are fine needle aspiration and core biopsy. Approximatelytwo million biopsies are performed in the United States each year.

The core biopsy technique—also known as Temno technique—is the oldestand most common biopsy technique on the market. Core biopsy devices areavailable as manually operated spring loaded or as fully automaticsystems. All devices use a coaxial needle set consisting of an innersolid needle (obdurator) in which a little pocket (notch) is grinded andan outer hallow needle, which is beveled to have a sharp tip. Theobdurator is pushed into the lesion and the surrounding tissue fills upthe notch. Then, the hallow outer needle moves fast forward cutting thetissue to leave a sharp cut specimen in the notch. Core biopsy deviceshave a couple of disadvantages:

Bending: Due to the beveled tip of the obdurator and the thin notchstrap, which makes the design unstable, the obdurator bends during itsforward movement through the tissue towards the opposite side of the tipbevel. This bending makes the core biopsy devices imprecise in targetingsmaller lesions.

Overshoot: Due to its mechanical design, core biopsy needles overshootthe targeted area by the length of the obdurator tip. A typically18-gauge prostate biopsy device will overthrow the lesion by 5-10millimeters and perforate the tissue on the distal other side of thelesion. Prostate cancer sites for instance are most likely been found inthe peripheral zone of the prostate. Because the prostate has a diameterof minimum 3 to 5 centimeters, core biopsies are limited to the innerportion if one wants to leave the prostate attaching tissue intact. Thesame problem occurs, when targeted breast tumor lesions are close to thelung pleura. In brain tissue every needle penetration in healthy tissuemay cause serious cognitive defects of the patient.

Artifact of needle tip under Magnetic Resonance Imaging (MRI): Due tothe mechanical design of core biopsy needles, the tip of the obduratorneedle is a solid piece of metal. Even if more MRI compatible materiallike titanium alloys are used for the material, this solid part causes arather large artifact at the tip of the obdurator, especially when theneedle is used in higher magnetic flux MRI tomographers, like 1.5 or 3.0Tesla.

Half Volume Sample: Due to the notch pocket of the core biopsy needle,the sample volume is only half the diameter of the column shapedobdurator. While this is not considered a serious problem, it does leadto the use of larger sized biopsy needles to obtain the desired samplevolume, while one could use a smaller needle size if the tissue samplewhere full column sized.

Torn Sample: While core biopsy devices work well in fatty tissue, theyoften have difficulties in more dense tissue. Here the cutting needleoften rather tears the tissue resulting in an insufficient tissue samplefor the pathological analysis.

Fine needle aspiration (FNA) biopsy techniques use a simple hallowneedle, which is placed into the tissue. Vacuum to perform theaspiration is either applied by a vacuum pump or in the simplest form byan expanded syringe. Vacuum aspiration biopsy devices lack thedisadvantage that they tear out the tissue and give imprecise specimencuts. Further this type of biopsy can only be accomplished with softerand easier to tear tissue. Prostate, breast or brain tissue is notrecommended for biopsy via aspiration.

The object of the here presented invention is to overcome above stateddisadvantages of today's biopsy devices. The invention provides a biopsymechanism which penetrated straight through the tissue without beingbended, does not overshoot the tissue lesion, does not create anabnormal image artifact and precisely cuts the desired tissue piece as afull circle specimen.

SUMMARY OF THE INVENTION

The suggested biopsy mechanism will cut the specimen in front of the tipof the guiding needle. The device may be guided by Magnetic ResonanceImaging (MRI), x-ray based techniques or ultrasound.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates the principle mechanism of the proposed biopsyprinciple.

FIG. 2 illustrates the difference in specimen gathered with

-   -   a.) conventional core biopsy and    -   b.) new proposed method, as described here.

FIG. 3 illustrated a possible driving mechanism for the biopsy device.

DETAILED DESCRIPTION

The new cutting mechanism cuts at the tip of a needle a dome likespecimen. FIG. 1 illustrates the basic new biopsy concept operating infive time snap shot stages. Only the distally located parts of theinstrument are shown; the proximal parts (handle) are not shown.

FIG. 1 a shows the access tube 2 in which an inner stylet 1 with atrocar like tip is positioned. This needle set is percutaneously pushedthrough the patients tissue until the tip of the stylet 1 is positionedat the location of planned biopsy.

In FIG. 1 b the inner stylet is withdrawn backwards and removed from theaccess tube 2. The access tube 2 now is rotated (arrow II) and pushedforward (arrow I) in distal direction. During this procedure tissue iscut by the cutting blade of the access tube 2 and a pillar like specimencollects within the access tube 2. The diameter of the specimen equalsthe inner diameter of the access tube 2, typically 1 mm to 4 mm. Thiscollecting of specimen can be supported by aspirating vacuum with helpof a pump or a syringe from the proximal side of the access tube 2.

FIGS. 1 c to 1 e now show how the specimen is planned to be cut at thedistal end of the instrument.

In FIG. 1 c a second tube, the cutting tube 4, is pushed from proximalto the distal direction over the access tube (arrow III). The cuttingtube 4 comprises a cutting blade 5 at its tip and constantly rotates(arrow IV). The cutting blade 5 of the cutting tube 4 is pre-bend insuch a way, that when overshooting the distal tip of the access tube2—FIG. 1 d—it bends back to its original form (arrow V). FIG. 1 e showsthe cutting blade 6 fully extended and bend back to its original form,which when rotated (arrow IV) is a dome like or half sphere form. Thecombination of forward-movement (arrow III) over the edge of the accesstube tip and rotation (arrow IV) now cuts the dome like form from thetissue specimen, leaving a circular pillar of specimen in the accesstube 2 with dome like circular tip.

The difference in specimen quality of a conventional core biopsy systemand one as here proposed considering the same needle diameter and lengthis explained using FIG. 2. FIG. 2 a illustrated a specimen of aconventional core biopsy needle. Due to the notch geometry the form ofthe gathered specimen is a half-circular pillar like. Because the tip ofthe obdurator needle penetrates through the biopsied lesion into thehealthy tissue on the opposite side of the lesion, the tissue there isdamaged, as illustrated in FIG. 2 a with dashed lines. In opposite, thenew proposed biopsy mechanism gives a true circular pillar like specimenwith a calf circular dome on the distal top. The here new proposedbiopsy mechanism will give more than 50% more pathological specimen,using the same needle diameter and length. Typical diameters and lengthof this mechanism are 1 mm to 3 mm in diameter and 10 mm to 12 mm inlength, as pathologists are used to. The here new proposed biopsymechanism leaves healthy tissue in tact.

The device may be made from stainless steel, Nivaflex®,titanium-vanadium-alloy, plastic, carbon fibre or nickel-titanium(NiTi). Typically the wall-thickness of any tube is between 0.01millimetres and 0.5 millimetres. The access tube comprises a relative toits tube diameter small cutting blade. The cutting blade of the cuttingtube may be made from different material as the cutting tube. Thecutting blade of the cutting tube is pre-bend inwards to the centre ofthe cutting tube and its tip locates at the centre or beyond of thecutting tube. The cutting blade is welded or glued onto the cuttingtube. The cutting blade is bending backwards when the cutting tube issliding over the access tube. The movements of any tube are manuallyoperated or motor driven. The gathered specimen has a typical diameterof 1 mm to 4 mm and length of 10 mm to 12 mm in length.

FIG. 3 illustrated a possible driving mechanism for the biopsy device inprinciple. The biopsy needle system 11 with rotating tip mechanism 16 ismounted in a hand held piece 12. A motor unit 14 generates the rotafion,which is transferred via a gear unit or transmission 15 to the needlesystem. A control mechanism (knob) 13 starts or stops the rotation.

1. A method to obtain tissue specimen using a device having an innersolid stylet with a bevelled tip, a hallow access tube and hallowcutting tube, whereas hallow cutting tube carries a pre-bend and inwardscutting blade on its tip, comprising the following procedural steps:pushing forward the inner stylet through the tissue until its tipreaches the targeted lesion; pushing forward the access tube slidingover the stylet until its tip reaches the targeted lesion; pulling backthe inner stylet; rotating and pushing forward the cutting tube over andaround the access tube until the cutting blade is fully bended to itsunbend position.
 2. The method of claim 1, wherein the forward speed ofthe access tube is between 0.1 millimetres per second and 100millimetres per second.
 3. The method of claim 1, wherein the forwardspeed of the cutting tube is between 0.1 millimetres per second and 100millimetres per second.
 4. The method of claim 1, wherein the rotationspeed of the cutting tube is between 0.1 rounds per second and 10,000rounds per second.
 5. The method of claim 1, wherein tissue is drawninto the access tube by applying vacuum pressure to the proximal side ofthe access tube.
 6. The method of claim 1, wherein the device is guidedby one or any combination of the group of imaging methods consisting ofx-ray fluoroscopy, computer tomography, magnetic resonance, ultrasound,visual, positron emission tomography or single photon emission computedtomography.
 7. A device to obtain tissue specimen, comprising an innersolid stylet with bevelled tip, a hallow access tube and hallow cuttingtube, whereas hallow cutting tube carries a pre-bend and inwards cuttingblade on its tip.
 8. The device of claim 7, whereas any tube, any partof a tube or the stylet is made from stainless steel, Nivaflex®,titanium-vanadium-alloy, plastic, carbon fibre or nickel-titanium. 9.The device of claim 7, whereas any wall-thickness of any tube is between0.01 millimetres and 0.5 millimetres.
 10. The device of claim 7, whereasthe access tube comprises a relative to its tube diameter small cuttingblade.
 11. The device of claim 7, whereas the cutting blade of thecutting tube is of different material as the cutting tube.
 12. Thedevice of claim 7, whereas the cutting blade of the cutting tube ispre-bend inwards to the centre of the cutting tube and its tip locatesat the centre or beyond of the cutting tube.
 13. The device of claim 7,whereas the cutting blade is welded or glued onto the cutting tube. 14.The device of claim 7, whereas the cutting blade is bend backwards whenthe cutting tube is sliding over the access tube.
 13. The device ofclaim 7, whereas the movements of any tube is manually operated.
 14. Thedevice of claim 7, whereas the movements of any tube is motor driven.15. The device of claim 7, wherein the gathered specimen has a typicaldiameter of 1 mm to 4 mm and length of 10 mm to 12 mm in length